It was formerly placed in the monotypic genus Limnogale,[3] but has been moved to Microgale based on molecular data showing it to be deeply nested within the latter.

[4] Microgale mergulus is strictly nocturnal, spending the day in stream side burrows, only emerging at night to hunt.

[5] The bulk of its diet consists of aquatic insects and larvae, with crustaceans (crayfish), small fish, and tadpoles making up the rest.

[9] All tenrecs are thought to descend from a common ancestor that lived 29–37 million years (Ma) ago[4][10][11] They include members of subfamilies Tenrecinae and Geogalinae as well as Oryzorictinae.

[8] While it is similar in habits to the related equatorial African otter shrews of family Potamogalidae, their aquatic lifestyles evolved independently from one another.

However, recent studies have shown healthy populations of M. mergulus in streams where forest has been cleared or otherwise degraded, as well as non-native plantations.